One approach could be to use a mask that is the shape of the halo and have an object spinning beneath it that is colored/filled with a sunburst sort of pattern... rays of color shades from a central point

What about what you tried didn't you like? If you describe what you did versus what you got, someone may be able to suggest a variation that you might like. For what I was suggesting, there would be a rotation (or two) about an axis, so I can't be sure you did what I suggested.